None that I know of. Why would one want a rack & pinion on a solid axle truck? Not trying to be a smart arse, but it would seem like a major limiting factor to articulation. Racks have to be mounted solid to the frame and the only parts that move up and down with the suspension is the tie rods. Considering the amount of movement a solid axle has, no rack could follow the same range of motion.
If you want to elminate the push-pull style of steering, get a 2wd box and the rest of the parts needed to do a x-over setup.